There are some tiny tin-box style games, often not very deep but maybe there is something out there worth traveling around with?
Star Realms is a solid little 2 player deck builder game! The base game is just a deck of cards and you dont need much room to play, so it’s a great portable game.
Our family usually packs Sushi Go and No Thanks when traveling
Hive Pocket goes on every vacation with me; its portable, indestructible, and can be played anywhere. Will also usually bring: Love Letter, Tides, SpaceShipped, and a deck of cards for Regicide/Scoundrel/Loot-The-Loop/etc. Will sometimes try to bring Bang! The Dice Game, Anomia, or Happy Salmon if there’s a potential for party games being played.
Love Letter
I recently travelled with the following small games and can recommend them.
Sprawlopolis - Lovely co-op city builder with 18 cards, much more replayable than you’d think.
Fugitive - A great cat and mouse/hidden movement game with numbered cards. Either flee as the fugitive or hunt as the marshal.
Air land and Sea - A tactical game with the added wrinkle of choosing when/if to withdraw.
Monopoly Deal - A classic, fast, fun, ruthless. Monopoly as it should be.
Hive Pocket - Chess like, strategic, tactile and can be played pretty much anywhere.
Stew - A simple bluffing card game of creating a stew together and working out when the best time is to eat the stew, if at all.
Hope this helps!